We consider orientation mechanisms for block copolymers in an electric field. Theoretical and experimental studies have shown that nonuniformity of the dielectric constant gives rise to a preferred orientation of the melt with respect to the applied field. We show that the presence of ions, as found in anionically prepared copolymers, may increase the alignment effect markedly. Time-varying (ac...

The synthesis and characterization of complex dendritic, rigid rod poly-2,7-fluorene homopolymers and copolymers via a macromonomer approach is reported. Several 2,7-dibromofluorene monomers containing benzyl ether dendrons (generations 1, 2, and 3) in the 9,9'-position of the fluorene ring were prepared and employed in condensation polymerizations to yield both homopolymers and copolymers with...

Synthesis, characterization and cytotoxicity evaluation of copolymers based on polyethylene glycol monmethyl ether-g-poly(methacrylic acid-co-methyl methacrylate) are reported via a polymeric precursor method. Grafting was accomplished based on direct condensation reaction in the presence of dicyclohexylcarbodiimide as an esterification-promoting agent catalyzed by dimethylamino pyridine. Polye...

Pluronic block copolymers are recognized pharmaceutical excipients listed in the US and British Pharmacopoeia. They have been used extensively in a variety of pharmaceutical formulations including delivery of low molecular mass drugs and polypeptides. This review describes novel applications of Pluronic block copolymers in gene therapy. In particular, these molecules can modify the biological r...

Starch-g-polyacrylonitrile (starch-g-PAN) copolymers were prepared by ceric ammonium nitrate initiation, and the major portion of the starch in these graft copolymers was then removed by acid hydrolysis to yield PAN with oligosaccharide end groups. Although these PAN-oligosaccharide samples reacted with methyl methacrylate in the presence of eerie ammonium nitrate, the resulting products were l...

Various thermally responsive block and graft copolymers based on poly(Nisopropylacrylamide) (PNIPA) have been synthesised. Poly(ethyleneoxides) (PEO) with different chain lengths were used as hydrophilic blocks and grafts. The graft copolymers were synthesised in two steps. Firstly, two functional copolymers were prepared by free radical polymerisation of N-isopropylacrylamide (NIPA) with eithe...

Graft copolymerization of binary vinyl monomers onto mercerized flax fiber was carried out for the enhancement of mechanical properties of polystyrene composites. Binary vinyl monomer mixture of AA+AN has been found to show maximum grafting (33.55%) onto mercerized flax. Graft copolymers thus synthesized were characterized with FT-IR spectroscopy, SEM, and TGA techniques. Mercerized flax (MF) s...

The solid-state structures, thermal properties, and enzymatic degradability of melt-crystallized films of random copolymers of (R)-3-hydroxybutyric acid (3HB) with different hydroxyalkanoic acids were investigated. The crystallinity, lamellar thickness, and spherulite growth rate of copolymers decreased with an increase in the carbon numbers of second monomer units for copolymers with an identi...

The crystallization behaviors of two copolymers of PVDF were studied, and the effect of copolymerized chains on the crystallization behavior was investigated. The results indicated that both copolymers had a lowered crystallization temperature and crystallinity. The crystallization rate was improved by the copolymer with symmetrical units in PVDF chains, but hindered by asymmetrical units, comp...

We describe an isomerization-alternating ROMP protocol that gives linear copolymers with rigorous sequence alternation. Bicyclo[4.2.0]oct-7-ene-7-carboxamides of primary amines are isomerized in the presence of (3-BrPyr)2Cl2(H2IMes)Ru=CHPh to the corresponding bicyclo[4.2.0]oct-1(8)-ene-8-carboxamides in which the olefinic bond is tetrasubstituted. The isomerized amides undergo alternating ring...